[Full-zirconia single-tooth molar implant-supported restorations with angulated screw channel abutments: evaluation of short-term outcomes].

Purpose: To evaluate the effect of full-zirconia single-tooth molar implant-supported restorations with angulated screw channel abutments.
Methods: Seventy-six patients with a single missing tooth in the posterior region of the maxilla and mandible underwent dental implants from March 2016 to March 2018 were enrolled. After 3 months, each patient received a full-contour screw-retained zirconia restoration with angulated screw channel abutment. Modified sulcus bleeding index (MSBI), modified plaque index (mPLI), periodontal probing depth (PD), marginal bone levels (MBLs) and mid-buccal mucosal levels (MBMLs) were recorded at the implantation moment (T0), four weeks (T1), one year (T2) and two years (T3) after treatment. During the follow-up period, the incidence of implant defects, survival rate and porcelain fracture were recorded. The data were processed using SPSS 23.0 software package.
Results: Of the 76 patients, 9 did not have a complete follow-up record (two of the implants failed before restoration, two patients had bilateral first molars missing, and five were lost to follow-up), and the remaining 67 patients with a total of 67 implants had a complete follow-up record. The success rate of implant was 97.01%(65/67) during one-year follow-up, and the initial success rate was 100% at an interval of three months. Compared with indexes at T0, mSBI and mPLI were significantly reduced at T1, T2 and T3 (P<0.05). There was no significant difference in PD level at T0, T1, T2 and T3(P>0.05), and the effective depth averaged 1.75 mm. Compared with indexes at T0, MBLs and MBMLs were significantly increased at T1(P<0.05). A total of 4 cases had implant reconstruction at T1 due to concerns about framework fracture, veneering fracture and aesthetics. At T2 and T3, there was no implant problems and loosening of restoration. There were 2 cases of peri-implant inflammation, one case of implant loss and one case of abutment pain, which were all improved after corresponding treatments. Two cases of porcelain fracture occurred in 67 zirconia restorations (2.63%), and the implant survival rate was 100%.
Conclusions: Full-zirconia single-tooth molar implant-supported restorations with angulated screw channel abutments can effectively improve the implant stability in early phase, with high success rate, good short-term effect and few complications.